The present invention relates generally to actuation systems for concurrently rotating a plurality of circumferentially spaced variable vanes, and, more specifically, to an actuator including means to maintain the angular position of the vanes within predetermined limits upon damage to the actuator caused by foreign objects.
Gas turbine engines are typically designed for accomodating the ingestion of foreign objects such as birds without a total failure of the engine. The engine may include an air intake having conventionally known variable inlet guide vanes (IGVs) which are rotatable over a predetermined angular position range.
One conventional manner of accommodating foreign object damage is to increase the strength of the IGVs by, for example, increasing the relative dimensions thereof. This arrangement may be undesirable because it adds additional weight and the increased size of the IGVs may adversely affect aerodynamic performance.
Furthermore, in the event an IGV is substantially damaged due to the impact of foreign objects and is thereby allowed to rotate independently of adjacent IGVs, a 1/REV excitation will be generated which can lead to high cycle fatigue damage of rotating blades in the engine.